Last week, MIT climate scientist and hurricane specialist Kerry Emanuel received email threats[1] for his view on climate change. These were quickly and appropriately condemned by the progressive and environmental blogosphere—as they are condemned by me–but I want to go a bit further and contemplate why Emanuel’s views in particular appear so menacing to some elements of the conservative base today.

The answer may seem deceptively simple on the surface: Unlike most climate researchers, Kerry Emanuel describes himself as a long time Republican. And he’s been speaking out lately. The precise catalyst leading to the emails was a video posted by Climate Desk[2], capturing Emanuel at an event in New Hampshire organized by maverick Republicans who actually accept global warming and don’t like the way their party is headed. They want to turn it around (hey, good luck with that).

So Emanuel is presumably seen as a turncoat by some Republicans and conservatives—and you might just leave it at that. But I think it is deeper. It is the kind of Republicanism that Emanuel represents—merged with his identity as a scientist, and a premiere one at that—that really presents the biggest challenge.

You see, Emanuel is what you might call an “Enlightenment Republican.”

He joined the party in the 1970s because he personally viewed it as the home of “reason” at a time of left wing excesses. As I wrote after I interviewed him[3] for the American Prospect magazine (Emanuel is also a featured personage in my book The Republican Brain[4]):

In the early 1970s, as an undergraduate at MIT, [Emanuel] remembers feeling surrounded by the “liberal excesses” then prevalent in the “People's Republic” of Cambridge, Massachusetts. “I remember hearing fellow students defending Pol Pot and Mao Zedong and Stalin, and I was so horrified,” he says. But now Emanuel sees the situation as reversed: The extremes are on the Tea Party right, the Democrats are centrists and pragmatists, and Emanuel–really always a moderate–finds not so much that he has moved but that his party has. “I'm turned off by those people for exactly the same reasons I was turned off by the ideologues of the 1970s,” he says.

Emanuel also made these comments to me:

“I don't like it when ideology trumps reason, and I see that the Republicans are guilty of that in spades at the moment,” he says.

“I've been toying with the idea of officially switching to independent status,” he adds.

In our interview, Emanuel also spoke of his admiration for the late William F. Buckley, Jr., the kind of person that today’s right sorely lacks—a sophisticated and nuanced intellectual in a position of leadership.

In other words, Emanuel’s story tells us just how much American politics have changed in the last three decades, and just what a cliff the GOP has fallen from in its relationship with science and reason.

In the 1960s and 1970s, if you thought the anti-war leftists on the campuses were overdoing it and you disliked ideological extremes, the Republican Party was a great place for you to go. Or at least, so it may have appeared at the time.

Even in the Reagan years, while there were certainly abuses against science there was also much more Republican rationalism and moderation—epitomized by Reagan’s joining the Montreal Protocol to curtail harmful stratospheric ozone depletion from CFCs.

This history, this legacy, led many people of reason–like Emanuel–to feel very comfortable within the Republican ranks. And once you forge a relationship with a political party and develop a loyalty, it is very hard to change it.

But the injuries to Republican reasoners have steadily mounted—from Newt Gingrich presiding over the destruction of congressional science advice in the mid 1990s, to the George W. Bush administration’s undermining of science at every turn, to the Tea Party and the near monolithic rejection of climate science by today’s GOP presidential candidates–and rationalists like Emanuel have a harder and harder time hanging on. Indeed, at this point they’re hanging by a thread.

What’s more, deep down, a lot of the right wing science deniers kind ofknow that they are pushing these people away.

Don’t get me wrong: They don’t actually believe that they’re factually incorrect. They don’t view themselves as “deniers.” But they definitely know that there is a huge amount of knowledge, intellect, and expertise that they’re flying in the face of. And they feel that disdain, as well as that bafflement, coming from the acknowledged centers of science and learning.

So when one of their “own,” Kerry Emanuel, comes along and states–from an expert scientific perspective–that they’re abandoning reason…the cognitive dissonance is just too great. And because they can’t admit the truth about themselves, they can only lash at the messenger.

Here’s the thing, though. Emanuel may have been a Republican for a very long time. But he and those New Hampshire moderates seeking to reclaim the party for science are, in my opinion, in for a “long wait for a train don’t come[5]” (to quote a really awesome sci-fi movie).

I fully understand their feelings of loyalty–and their desire to rescue what once was. But at the same time, I think they themselves probably recognize that the 60s and 70s—a time when, among other things, the Christian right was not fully integrated into the GOP–will never return. Heck, even I might have been a Republican in that era; I certainly find Frank Zappa’s songs making fun of hippies[6] pretty hilarious.

But that’s not the world we’re living in today—Republicanism and science just don’t go together much any longer. And the Republicans or conservatives who do stand up for rationality today—people like David Frum, Bruce Bartlett, and Kerry Emanuel—are most easily identified today by one chief characteristic: their banishment and alienation.